Effusion cells that are going to be used for face-down operation need a supplementary face-down assembly to prevent evaporation material from falling out of the cell.
In case of face-down operation, the downwards pointing cell crucible is equipped with a special face-down insert that holds the smaller, evaporant-containing crucible in upright position within the regular cell crucible.

The following figure shows a schematic of a typical face-down crucible assembly.

  1. Cell crucible in face-down position.
  2. Evaporant-containing crucible in upright position.
  3. Retaining insert, holding the inner crucible.